Proposed here are a series of studies, analyses of previously collected data, examining the role of dietary factors in carcinogenesis. Two types of studies are proposed: 1) case-control and 2) cohort. For the case- control studies, analyses will examine the role of dietary intake in premenopausal breast cancer, endometrial cancer and prostatic cancer. In particular, the association of fat, kilocalories, carotenoids, vitamins A, C and E, fiber, zinc and cruciferous vegetables will be investigated. In addition, data on the controls from the case-control studies will be utilized to examine the colinearity among other risk factors and dietary practices. For the cohort study, 56,000 older-term New York State residents, both males and females who completed a short questionnaire in 1980 regarding their usual dietary intake and data such as age, age at first birth and smoking practices have been followed. Sufficient cases have now accrued to allow for analysis of dietary factors in cancer of the lung, colo, rectum, ovary, endometrium and prostate. These investigations, combining retrospective, cross-sectional and prospective designs, will help to elucidate the role of dietary intake and nutrient status in carcinogenesis.